ML031900042
| ML031900042 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 07/01/2003 |
| From: | Rosalyn Jones Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML031900042 (12) | |
Text
-k.0 Ph Duke drPowere A Duke Energy Company R. A. JONES Vice President Duke Power 29672 / Oconee Nuclear Site 7800 Rochester Highway Seneca, SC 29672 864 885 3158 864 885 3564 fax July 1, 2003 U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Attention: Document Control Desk
Subject:
Oconee Nuclear Station Docket Numbers 50-269, 270, and 287 Technical Specification Bases (TSB) Change Please see attached revisions to Tech Spec Bases 3.1.7, CRDM Position Indication Channels, which were implemented on June 26, 2003. contains the new TSB pages and Attachment 2 contains the markup version of the Bases pages.
If any additional information is needed, please contact Larry E. Nicholson, at (864-885-3292).
Very t 1 yours, R.
es, Vice President Oconee Nuclear Site
%ooI www. duke-energy. corn
U. S. Nuclear Regulatory Commission July 1, 2003 Page 2 cc:
Mr. L. N. Olshan Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. L. A. Reyes, Regional Administrator U. S. Nuclear Regulatory Commission -
Region II Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mel Shannon Senior Resident Inspector Oconee Nuclear Station Mr. Henry Porter Director Division of Radioactive Waste Management Bureau of Land and Waste Management Department of Health & Environmental Control 2600 Bull Street Columbia, SC 29201
Position Indicator Channels B 3.1.7 B 3.1 REACTIVITY CONTROL B 3.1.7 Position Indicator Channels BASES BACKGROUND According to ONS Design Criteria (Ref. 1), instrumentation to monitor variables and systems over their operating ranges during normal operation, anticipated operational occurrences, and accident conditions must be OPERABLE. LCO 3.1.7 is required to ensure OPERABILITY of the CONTROL ROD and APSR position indicators, and thereby ensure compliance with the CONTROL ROD alignment and position limits and APSR alignment limits.
The OPERABILITY of the CONTROL RODS is an initial condition assumption in all safety analyses that assume rod insertion upon reactor trip. Maximum rod misalignment for the CONTROL RODS is assumed in the safety analysis, which directly affect core power distributions and assumptions of available SDM.
Mechanical or electrical failures may cause a CONTROL ROD or APSR to become misaligned from its group. CONTROL ROD or APSR misalignment may cause increased power peaking, due to the asymmetric reactivity distribution and a reduction in the total available CONTROL ROD worth for reactor shutdown. Therefore, CONTROL ROD and APSR alignment are related to core operation within design power peaking limits and the core design requirement of a minimum SDM. CONTROL ROD and APSR position indication is needed to assess rod OPERABILITY and alignment.
Umits on CONTROL ROD and APSR alignment and group position have been established, and all CONTROL ROD and APSR positions are monitored and controlled during power operation to ensure that the power distribution-andreactivitylirnitsdefined-by-the -desigripowerpeakling-and SDM limits are preserved.
Two methods of CONTROL ROD and APSR position indication are provided in the Rod Drive Control System. The two means are by absolute position indicator and relative position indicator transducers. The absolute position indicator transducer consists of a series of magnetically operated reed switches mounted In a tube parallel to the control rod drive mechanism CRDM) motor tube extension.
OCONEE UNITS 1, 2, & 3 B 3.1.7-1 BASES REVISON DATED 06/26/03 I
Position Indicator Channels B 3.1.7 BASES BACKGROUND (continued)
Switch contacts close when a permanent magnet mounted on the upper end of the CONTROL ROD and APSR assembly (CRA) leadscrew extension comes near. As the leadscrew and CONTROL ROD or APSR move, the switches operate sequentially, producing an analog voltage proportional to position. Other reed switches included in the same tube with the absolute position Indicator matrix provide full in and full out limit indications, and absolute position indications at 0%, 25%, 50%, 75%,
and 100% travel. This series of seven indicators are called zone reference indicators. The relative position indicator transducer Is a potentiometer, driven by a pulse stepping motor that produces a signal proportional to CONTROL ROD or APSR position, based on the electrical pulse steps that drive the CRDM.
Two absolute position indicator channel designs may be used in the unit:
type A absolute position indicators and type R4C absolute position indicators. The type A absolute position indicator transducer is a voltage divider circuit made up of 48 resistors of equal value connected in series.
One end of 48 reed switches is connected at a junction between each of the resistors, so that as the magnet mounted on the leadscrew moves, either one or two reed switches are closed in the vicinity of the magnet.
The type R4C (redundant four channel) absolute position indicator transducer has two parallel sets of voltage divider circuits made up of 36 resistors each, connected in series (channels A and B). One end of 36 reed switches Is connected at a junction between each of the resistors of the two parallel circuits. The reed switches malting up each circuit are offset, such that the switches for channel A are staggered with the switches for channel B. The type R4C Is designed such that either two or three reed switches are closed in the vicinity of the magnet. By its design, the type R4C absolute position ndicator provides redundancy, with the two three sequence of pickup and drop out of reed switches to enable a continuity of position signal when a single reed switch falls to close.
CONTROL ROD and APSR position indicating readout devices located in
-~the con
-room consioingle rposition metersoneaposition indication panel. A selector switch permits either relative or absolute position indication to be displayed. Indicator lights are provided on the position indication panel to indicate when each CONTROL ROD or APSR is fully withdrawn, fully inserted, or enabled, and whether a rod position asymmetry alarm condition Is present. Altemate indicators show full insertion, full withdrawal, and under control for each CONTROL ROD and APSR group.
OCONEE UNITS 1, 2, & 3 B 3.1.7-2 BASES REVISON DATED 06126/03
Position Indicator Channels B 3.1.7 BASES (continued)
APPLICABLE SAFETY ANALYSES CONTROL ROD and APSR position accuracy Is essential during power operation. Power peaking, ejected rod worth, or SDM limits may be violated In the event of a Design Basis Accident (Ref. 2) with CONTROL RODS or APSRs operating outside their limits undetected. CONTROL ROD and APSR positions must be known in order to verify the core is operating within the group sequence, overlap, design peaking limits, ejected rod worth, and with minimum SDM (LCO 3.1.5, 'Safety Rod Position Umits' and LCO 3.2.1, Regulating Rod Position Umits").
CONTROL ROD and APSR positions must be known in order to verify the alignment limits are preserved (LCO 3.1.4, CONTROL ROD Group Alignment Umits' and LCO 3.1.6, AXIAL POWER SHAPING ROD (APSR)
Alignment Umits"). CONTROL ROD and APSR positions are continuously monitored to provide operators with information that ensures the unit is operating within the bounds of the accident analysis assumptions.
The CONTROL ROD and APSR position indicator channels satisfy Criterion 2 of 10 CFR 50.36 (Ref. 3).
LCO LCO 3.1.7 specifies that one position indicator channel be OPERABLE for each CONTROL ROD and APSR.
This requirement ensures that CONTROL ROD and APSR position indication during MODES 1 and 2 and PHYSICS TESTS is accurate, and that design assumptions are not challenged. OPERABILITY of the position indicator channel ensures that Inoperable, misaligned, or mispositioned CONTROL RODS or APSRs can be detected. Therefore, power peaking and SDM can be controlled within acceptable limits.
APPLICAI3ILITY In MODES 1 and 2, OPERABILITY of the position indicator channel is required, since the reactor is, or is capable of, generating THERMAL POWER in these MODES. In MODES 3,4, 5, and 6, Applicability is not required-because-thefeacts-shtdown h-therequired-minimumSDM and is not generating THERMAL POWER.
ACTIONS A.1 If the required position indicator channel is inoperable for one or more rods, the position of the CONTROL ROD or APSR is not known with certainty.
Therefore, each affected CONTROL ROD or APSR must be declared inoperable, and the limits of LCO 3.1.4 or LCO 3.1.6 apply. The required OCONsEE UNITS 1, 2, & 3 B 3.1.7-3 BASES REVISON DATED 06/26/03
Position Indicator Channels B3.1.7 BASES (continued)
ACTIONS A.1 (continued)
Completion Time for declaring the rod(s) inoperable is immediately.
Therefore, LCO 3.1.4 or LCO 3.1.6 Is entered immediately, and the required Completion Times for the appropriate Required Actions in those LCOs apply without delay.
SURVEILLANCE SR 3.1.7.1 REQUIREMENTS A CHANNEL CHECK of the required position indication channel ensures that position indication for each CONTROL ROD and APSR remains OPERABLE and accurate. This CHANNEL CHECK will detect gross failures. The required Frequency of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is adequate for verifying that no degradation in system OPERABILITY has occurred.
REFERENCES
- 1.
UFSAR, Section 3.1.
- 2.
UFSAR, Chapter 15.
- 3.
OCONEE UNITS 1, 2, & 3 B 3.1.7-4 BASES REVISON DATED 06/26/03
Position Indicator Channels B 3.1.7 B 3.1 REACTIVITY CONTROL B 3.1.7 Position Indicator Channels BASES BACKGROUND According to ONS Design Criteria (Ref. 1), instrumentation to monitor variables and systems over their operating ranges during normal operation, anticipated operational occurrences, and accident conditions must be OPERABLE. LCO 3.1.7 is required to ensure OPERABILITY of the CONTROL ROD and APSR position Indicators, and thereby ensure compliance with the CONTROL ROD alignment and position limits and APSR alignment limits.
The OPERABILITY of the CONTROL RODS is an Initial condition assumption in all safety analyses that assume rod insertion upon reactor trip. Maximum rod misalignment for the CONTROL RODS is assumed in the safety analysis, which directly affect core power distributions and assumptions of available SDM.
Mechanical or electrical failures may cause a CONTROL ROD or APSR to become misaligned from s group. CONTROL ROD or APSR misalignment may cause increased power peaking, due to the asymmetric reactivity distribution and a reduction in the total available CONTROL ROD worth for reactor shutdown. Therefore, CONTROL ROD and APSR alignment are related to core operation within design power peaking limits and the core design requirement of a minimum SDM. CONTROL ROD and APSR position indication Is needed to assess rod OPERABILITY and alignment.
Umits on CONTROL ROD and APSR alignment and group position have been established, and all CONTROL ROD and APSR positions are monitored and controlled during power operation to ensure that the power distWbution and reactivity limits defined by the design power peaking and SDM limits are preserved:
Two methods of CONTROL ROD and APSR position indication are provided in the Rod Drive Control System. The two means are by absolute position indicator and relative position indicator transducers. The absolute position Indicator transducer consists of a series of magnetically operated reed switches mounted in a tube parallel to the control rod drive mechanism (CRDM) motor tube extension.
OCONEE UNITS 1, 2, & 3 B 3.1.7-1 BASES REVISON DATED OI2xx/W03 I
Position Indicator Channels B 3.1.7 BASES BACKGROUND (continued)
Switch contacts close when a permanent magnet mounted on the upper end of the CONTROL ROD and APSR assembly (CRA) leadscrew extension comes near. As the leadscrew and CONTROL ROD or APSR move, the switches operate sequentially, producing an analog voltage proportional to position. Other reed switches included in the same tube with the absolute position indicator matrix provide full in and full out limit indications, and absolute position indications at 0%, 25%, 50%, 75%,
and 100% travel. This series of seven indicators are called zone reference indicators. The relative position Indicator transducer is a potentiometer, driven by a pulse stepping motor that produces a signal proportional to CONTROL ROD or APSR position, based on the electrical pulse steps that drive the CRDM.
Type R4C (redundant four channel) transducers are used for absolute position indicators. Two absolute position indicator channel designs may be used in the unit: type A absolute position indicators and typo RIC abseol6t pocitien MIdiators. The po A absolute positien indicatr transducer is a voltage dMdor circuit made up of 18 resistors of equal value Geoneoctd lin coros. One end of 18 reod P.tches is Gonnectod at a juntin betWeen e oh of the esiste, so that as the magnet mounted on the ladscrew moves, either one or tw reod swirhes are losed in the vicinit'y of the magnet. The Each type R4C (redundant four channel) absolute position indicator transducer has two parallel sets of voltage divider circuits made up of 36 resistors each, connected In series (channels A and B). One end of 36 reed switches is connected at a junction between each of the resistors of the two parallel circuits. The reed switches making up each circuit are offset, such that the switches for channel A are staggered with the switches for channel B. The type R4C is designed such that either two or three reed switches are closed in the vicinity of the magnet. By its design, the type R4C absolute position Indicator provides redundancy, with the two three sequence of pickup and drop out of reed switches to enable a continuity of position signal when a single reed switch fails to close.
CONTROL ROD and APSR position Indicating readout devices located in the control room consist of single rod position meters on a position indication panel. A selector switch permits either relative or absolute position ndication to be displayed. Indicator lights are provided on the position indication panel to Indicate when each CONTROL ROD or APSR is fully withdrawn, fully inserted, or enabled, and whether a rod position asymmetry alarm condition is present. Altemate indicators show full insertion, full withdrawal, and under control for each CONTROL ROD and APSR group.
OCONEE UNITS 1 2 3
B 3.1.7-2 BASES REVISON DATED 06/25IO2xxfx0x3 I
Position Indicator Channels B 3.1.7 BASES (continued)
APPLICABLE SAFETY ANALYSES CONTROL ROD and APSR position accuracy is essential during power operation. Power peaking, ejected rod worth, or SDM limits may be violated in the event of a Design Basis Accident (Ref. 2) with CONTROL RODS or APSRs operating outside their limits undetected. CONTROL ROD and APSR positions must be known in order to verify the core is operating within the group sequence, overlap, design peaking limits, ejected rod worth, and with minimum SDM (LCO 3.1.5, "Safety Rod Position Limits" and LCO 3.2.1, "Regulating Rod Position Umits").
CONTROL ROD and APSR positions must be known in order to verify the alignment limits are preserved (LCO 3.1.4, "CONTROL ROD Group Alignment Umitse and LCO 3.1.6, "AXIAL POWER SHAPING ROD (APSR)
Alignment imits"). CONTROL ROD and APSR positions are continuously monitored to provide operators with information that ensures the unit is operating within the bounds of the accident analysis assumptions.
The CONTROL ROD and APSR position indicator channels satisfy Criterion 2 of 10 CFR 50.36 (Ref. 3).
LCO LCO 3.1.7 specifies that one position indicator channel be OPERABLE for each CONTROL ROD and APSR.
This requirement ensures that CONTROL ROD and APSR position indication during MODES I and 2 and PHYSICS TESTS is accurate, and that design assumptions are not challenged. OPERABILITY of the position indicator channel ensures that inoperable, misaligned, or mispositioned CONTROL RODS or APSRs can be detected. Therefore, power peaking and SDM can be controlled within acceptable limits.
APPLICABILITY In MODES I and 2, OPERABILITY of the position indicator channel is required, since the reactor is, or is capable of, generating THERMAL POWER in these MODES. In MODES 3,4, 5, and 6, Applicability is not required because the reactor is shut down with the required minimum SDM and Is not generating THERMAL POWER.
ACTIONS A.1 If the required position Indicator channel is inoperable for one or more rods, the position of the CONTROL ROD or APSR is not known with certainty.
Therefore, each affected CONTROL ROD or APSR must be declared inoperable, and the limits of CO 3.1.4 or LCO 3.1.6 apply. The required OCONEE UNITS 1 2 3
B 3.1.7-3 BASES REVISON DATED 02Oxxlxx/03 I
Position Indicator Channels B 3.1.7 BASES (continued)
ACTIONS A.1 (continued)
Completion Time for declaring the rod(s) inoperable is immediately.
Therefore, LCO 3.1.4 or LCO 3.1.6 is entered immediately, and the required Completion Times for the appropriate Required Actions in those LCOs apply without delay.
SURVEILLANCE SR 3.1.7.1 REQUIREMENTS A CHANNEL CHECK of the required position indication channel ensures that position indication for each CONTROL ROD and APSR remains OPERABLE and accurate. This CHANNEL CHECK will detect gross failures. The required Frequency of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Is adequate for verifying that no degradation in system OPERABILITY has occurred.
REFERENCES
- 1.
UFSAR, Section 3.1.
- 2.
UFSAR, Chapter 15.
- 3.
OCONEE UNITS 1, 2, & 3 B 3.1.7-4 BASES REVISON DATED 6/52x/xx/O03 I